The present invention pertains to the art of liquid dispensers, and, more particularly, to a dispensing tip for accurately dispensing small droplets of liquid. The invention is particularly applicable for use as an eyedropper to dispense ophthalmic drugs and will be described with particular reference thereto although it will be appreciated that the invention has other and broader applications.
Medicant drop dispensers of the type to which the present invention pertains are available in various sizes and shapes for the numerous medicines and solutions which are available for the care and comfort of the human eye. Such dispensers are basically comprised of a relatively small compressible plastic container or vial provided with a dispensing tip and cap.
One problem associated with conventional eyedroppers is the difficulty in accurately controlling the amount of medicine dispensed, i.e., the number of drops dispensed. Many conventional eyedroppers utilize one or a combination of methods to achieve single drop control.
One method uses a highly compliant plastic bottle which the user squeezes to dispense a drop. The extensive deflection of the bottle creates an significant internal air pressure within the vial which expels the liquid through the tip. In order to prevent a continuous stream of liquid medicant from being expelled, and to create single drops, these bottles sometimes incorporate a flow restriction at the inlet of the tip or nozzle. This flow restriction tends to limit the number of drops expelled during a single squeeze. It limits the liquid medicant flow rate favoring the formation of individual drops releasing from the dropper tip rather than a continuous stream. Unfortunately, the creation of a very small molded orifice, frequently as small as 0.005" (0.13 mm) in diameter creates manufacturing difficulties, since the plastic injection molds must have corresponding small fragile (0.005" dia./0.13 mm dia.) core pins.